Using ValueChangeListeners with Datatable

I have a datatable with 2 columns and a number of rows. The first column contains a selectone listbox and the next column contains a textbox. My objective is to select an option from the drop down list and to get the selected value to show up on the textbox(Only in that purticular row).

I tried to do this by attaching an ValueChangeListener to the selectBox. I expected the valueChangeListener function to be called once. Instead, it gets called once for every row in the datatable.

Some Background Info: ---------------------- SampleBean is a request scope managed bean SampleBean's attribute is an arry of TableBean (i.e. TableBean[]) TableBean contains 2 attributes: An SelectItem[] and a String. Thus, each row in the datatable corresponds to one TableBean. I tried having the valueChangeListener() placed in both the SampleBean and the TableBean, but still have the same problem of multiple calls.